1. Field of the Invention
This invention relates to a disk replication apparatus, and more particularly is applicable, for example, to the manufacture of a stamper of a compact disk.
2. Description of the Related Art
Conventionally, compact disks are manufactured in a large quantity by using a predetermined stamper which has been previously provided.
More specifically, as shown in FIG. 1, in a compact disk manufacturing process, first, audio data composed of a digital audio signal is input to an editing unit to edit the audio signal by the unit.
Further, in this compact disk manufacturing process, a data layout on the compact disk is determined based on the edited audio signal in a mastering process and recording data with the recording format of the compact disk is generated in accordance with the data layout.
Further, in the mastering process, the recording data is encoded to a CD (compact disk) signal and then a stamper is made by using the CD signal.
In the mastering process, an original master disk for manufacturing compact disks is made in such a manner that a glass substrate on which photoresistor is coated, for example, is irradiated with a laser beam modulated by the CD signal and developed, and in a succeeding stamper process, a stamper for manufacturing the compact disks is made from the master original disk.
With this arrangement, in the compact disk manufacturing process, compact disks are manufactured in a large quantity by using the stamper and applying a method such as, for example, injection molding.
Incidentally, some compact disks can record various data by using the recording format of audio data (that is, they are composed of a CD-ROM).
As shown in FIG. 2, the CD-ROM has three kind of modes, i.e., mode 0 to mode 2 and in each mode desired data are converted into frame data in accordance with a predetermined format and then the converted data are further converted into recording data in accordance with the audio format of a compact disk.
However, in the CD-ROM, two kinds of formats, i.e. a form 1 and a form 2 are given to the third mode, i.e. the mode 2 out of the three kinds of modes, which permits the selection of various formats in accordance with the user data to be recorded.
Here, as shown in FIG. 3, in the compact disk, a channel of a subcode Q can be demodulated by demodulating a reproduction signal S1 being an EFM modulation signal, which is obtained by reproducing the compact disk, at an EFM demodulation circuit 1, which permits to detect the address data of recorded data.
Further, in the compact disk, a channel of a subcode R-W can be reproduced by correcting the error of a signal output from the EFM demodulation circuit 1 at an error correction processing circuit 3, which permits to reproduce image data and the like recorded to the channel of the subcode R-W.
On the other hand, a channel of audio data AU can be reproduced in such a manner that a signal output from the EFM demodulation circuit 1 is input to an error correction circuit 4 to correct the error thereof by using cyclic code, and the audio data is converted into an analog signal to reproduce an audio signal.
When the data of a CD-ROM is also reproduced, the sync pattern is detected at a synchronization detection circuit 5 to cut out continuous frame data in a predetermined block unit and the frame data is sequentially descrambled by a descramble circuit 6 in each block unit.
With this arrangement, in the formats of mode 0 and the form 2 of the mode 2 of the CD-ROM, it is found that desired data can be recorded to a compact disk in such a manner that the desired data is divided into the predetermined block unit and subjected to a scramble processing and added with sync data to form frame data and continuous frame data is processed in the same way as audio data.
On the other hand, in the mode 1 and the form 1 of the mode 2 of the CD-ROM, data output from the descramble circuit 6 can be demodulated by further correcting the error of the data at an error correction circuit 7.
With this arrangement, in the mode 1 and the form 1 of the mode 2 of the CD-ROM, it is found that frame data can be generated in such a manner that desired data is divided into a predetermined block unit and added with an error correction code and then processed in the same way as the mode 2 of the CD-ROM, and the frame data can be recorded to a compact disk by processing it in the same way as audio data.
With arrangement, this type of CD-ROMs can provide computer software and the like in a large quantity by the mass-producing them by using a master disk.
Incidentally, a drawback arises in that although computer software and the like must be debugged by operating it in an actual system, this type of the CD-ROM cannot repeat a debugging process in a short time because a master disk must be made.
A method of overcoming this drawback is to make a CD-ROM by using a write once type optical disk.
More specifically, in the write once type optical disk, desired information can be recorded only once by irradiating a light beam in accordance with recording information.
Therefore, when the CD-ROM is made by using the write once type optical disk, a debugging processing can be repeated in a short time.
It is contemplated to be convenient to make the stamper of a CD-ROM by replicating the CD-ROM subjected to a debugging processing as it is.
However, as described above with respect to FIG. 1, in a conventional compact disk manufacturing process, after data is edited at an editing unit, then the data layout on a compact disk is determined in a mastering process and a data train is generated by the recording format of the compact disk in accordance with the data layout. As a result the optical disk having been debugged as described above cannot make a stamper unless it is returned to its original data format once, and, thus a problem arises in that time is needed to make the stamper.
Further, when the optical disk is retuned to its original data format once, a problem also arises in that the positional relationship of frame data and the channel of the subcode Q composed of the address data of the frame data is unavoidably changed to the CD-ROM as a replication source.
More specifically, in reproduction, this type of the CD-ROM sets a time until corresponding frame data is detected to a desired time after it detects a channel of a subcode Q by setting a positional relationship of the channel of the subcode Q so that it corresponds to the frame data. Therefore, when the positional relationship is changed in this CD-ROM, there is a possibility that the frame data cannot be correctly reproduced or a processing program for processing the frame data cannot correctly operate.
Further, when the optical disk is returned to its data format once, the management of data is time-consuming in a CD-ROM in which audio data, video data, frame data and the like mixedly exist.
Although it may be contemplated to generate a CD signal by output data output from the EFM demodulation circuit 1 as a method of solving this problem, there is a possibility in this case that CD-ROMs made by mass-production cannot correctly reproduce data due to the accumulation of errors caused in reproducing.